[FFmpeg-devel] [PATCH 4/4] avcodec/targa: Do not return images when there is no image in the tga

[Anton Khirnov]

Quoting Michael Niedermayer (2021-12-03 15:04:47)
> On Sat, Sep 18, 2021 at 06:27:15PM +0200, Michael Niedermayer wrote:
> > On Fri, Sep 17, 2021 at 08:06:48PM +0200, Paul B Mahol wrote:
> > > On Fri, Sep 17, 2021 at 8:00 PM Michael Niedermayer <michael at niedermayer.cc>
> > > wrote:
> > > 
> > > > On Fri, Sep 17, 2021 at 07:35:32PM +0200, Paul B Mahol wrote:
> > > > > Please do not apply, This actually changes output to nothing.
> > > >
> > > > Do you have such a TGA file without an image in it?
> > > >
> > > > Why would that be relevant, comply with TGA specifications please.
> > > 
> > > thx
> > 
> > It is relevant as it would allow to check how such a file is handled
> > by various implementations
> > The specification does not specify that. It just says 
> > "No image Data included"
> > and our decoder returns a black image, the specification doesnt say that
> > means "black image" or i missed it when reading 
> > after the patch the decoder returns nothing instead of a black image
> > The other type this might reach is type 8, the specification i have doesnt
> > say anything about type 8 except that its reserved
> > 
> >     Truevision TGAa
> > FILE FORMAT SPECIFICATION
> > Version 2.0
> > ...
> > Image Type - Field 3 (1 byte):
> > The TGA File Format can be used to store Pseudo-Color, True-Color and Direct-Color images of various
> > pixel depths. Truevision has currently defined seven image types:
> > image       Description
> > Type    0   No image Data included
> 
> ping
> what do you prefer for this issue ?
> Id like to do something here not just ignore it even if the conclusion is
> that this is "not a bug but intended behavior"

A brief look at other opensource decoders suggest they don't support
type==0 at all. image-rs does, but it's not clear to be what its output
is. I'd say not returning a frame is reasonable.

-- 
Anton Khirnov